Stacking unit for articles sheet form

ABSTRACT

Stacker  1  for sheet-shaped objects is described having feeding device  3  for depositing sheet-shaped objects  2  in storage pocket  4  with variable capacity. Storage pocket  4  has contact surface  5  against which sheet-shaped objects  2  deposited in storage pocket  4  lie with one edge  6 , and storage tray  7  on which sheet-shaped objects  2  are stacked in storage pocket  4  flat and parallel to storage tray  7 . Storage tray  7  is mounted movably for changing the capacity of storage pocket  4 . Storage pocket  4  is disposed with contact surface  5  at an angle to the horizontal so that sheet-shaped objects  2  stacked in storage pocket  4  rest with their edges  6  on contact surface  5  and the resulting frictional force between edges  6  of sheet-shaped objects  2  and contact surface  5  substantially compensates the slope descending force acting on stack  10  formed of sheet-shaped objects  2  in the direction of storage tray  7 . Feeding device  3  exerts a force on stack  10  when depositing sheet-shaped object  2  at least as of certain stack thickness c, thereby moving storage tray  7  so as to enlarge the capacity of storage pocket  4.

[0001] The present invention relates to a stacker for sheet-shapedobjects, in particular bank notes, having a feeding device fordepositing the sheet-shaped objects in a storage pocket with variablecapacity.

[0002] Stackers for flat sheet-shaped objects are used in particular inautomatic sorters, testers and counters, for example for bank notes, forreceiving or temporarily storing the objects after testing, sorting andcounting. Simple stackers normally have a storage pocket of fixed sizethat is intended for example for precisely 100 bank notes of a certainthickness. In addition, DE 27 29 830 C2 discloses a bank note sortingdevice wherein sorted bank notes are stacked in storage containers, thesize of the storage containers being variable in accordance with thestack height of the notes. For this purpose a baseplate on which thenotes are deposited is lowered by means of a threaded spindle forreceiving the growing bank note stack in the storage container. Suchstackers are thus not limited to a fixed number of notes. However,elaborate control is required for the threaded spindle for changing thesize of the storage container.

[0003] In addition, FR 2 561 632 A1 discloses a sorting apparatus forletters wherein letters are received in a storage container having acontact surface inclined 10° to the horizontal, on which the edges ofthe letters rest.

[0004] It is the problem of the present invention to develop the knownprior art for bank notes.

[0005] This problem is solved by a stacker according to claim 1.Advantageous embodiments of the invention are stated in the claimsdependent thereon.

[0006] As in known stackers, the inventive stacker has feeding devicefor depositing the sheet-shaped objects in a storage pocket. The storagepocket likewise has a storage tray on which the sheet-shaped objects arestacked flat and parallel to the storage tray, and a contact surfaceagainst which the sheet-shaped objects lie with one edge. It isexpressly pointed out that the term “storage tray” refers here not onlyto a continuous tray but also to a tray in the form of a grid, a singlebar or a plurality of side-by-side bars grasping under the stack like afork for example. Also, the contact surface need not necessarily be acontinuous surface but can likewise be formed of bars or the like.

[0007] In contrast to known stackers, the contact surface of the storagepocket is disposed at an angle to the horizontal in the inventivestacker so that the sheet-shaped objects stacked in the storage pocketrest with their edges on the contact surface and the resultingfrictional force between the edges of the sheet-shaped objects and thecontact surface substantially compensates the slope descending forceacting on the stack of sheets in the direction of the storage tray. Thatis, the stack is located roughly in equilibrium independently of themass of the stack. The precise angle of inclination at which slopedescending force and frictional force are compensated depends on thecoefficient of friction of the paper edges on the contact surface andcan vary depending on the type of sheet material. It has turned outthat, for paper notes and a metal contact surface, the ideal angle ofinclination of the contact surface is normally between 20° and 30° tothe horizontal, preferably about 20.

[0008] The feeding device is designed or disposed so as to exert a forceon the stack when depositing a sheet-shaped object at least as of acertain stack thickness, thereby moving the storage tray so as toenlarge the capacity of the storage pocket. Thus, a passive guidance isinvolved here that does without any control. The size of the storagepocket adapts automatically to the stack thickness. Since the system isindependent of the mass of the stack, functioning is guaranteed for allbank note formats. It is to be heeded that the total weight of a banknote stack can fluctuate considerably depending on the type of note andis therefore normally very relevant. For 500 notes for example, thetotal weight is between 250 and 750 grams depending on the type of note.

[0009] In an especially preferred embodiment, the storage tray is urgedinto a starting position by means of a spring element and displacedagainst this spring force by the feeding device. The spring elementensures firstly that the storage tray is returned automatically to thestarting position upon removal of the stack and does not have to bemoved back to the starting position by hand. Secondly, the springelement slightly counteracts the shearing force produced by the feedingdevice during stacking. Due to this bias, the storage tray is displacedby the feeding device during stacking of a sheet-shaped object only bythe required path, i.e. by the thickness of the stacked object. Thestack of sheets is thus quasi clamped between the element of the feedingdevice exerting the force on the stack from above and the storage tray.

[0010] The spring element can be for example an extension spring, acompression spring or a pneumatic or hydraulic element. The springconstant should be dimensioned so as to guarantee a minimum biasingforce so that the storage tray is reliably guided back upon removal ofthe stack even if the device is relatively old, partly worn out orsoiled. On the other hand, the spring constant should be as low aspossible so that the change of spring tension is minimal upondisplacement of the storage tray, i.e. when the stack becomes larger.Thus, the force to be applied to the stack of sheets by the feedingdevice is negligibly low even at maximum stack height, on the one hand,and the change of force over the displacement path of the storage trayis likewise negligibly low, on the other hand.

[0011] The feeding device selected can be in principle any device thatexerts a force on the stack when depositing a sheet-shaped object. Acustomary spiral slot stacker is preferably used which has a stackingwheel whose fingers press on the stack when depositing a sheet-shapedobject.

[0012] The invention will be explained in more detail in the followingwith reference to the enclosed drawing on the basis of an example. Thefeatures set forth there as well as the features described above can beessential to the invention not only in the stated combination but alsoindividually or in other combinations.

[0013] The single FIGURE shows a schematic side view of an inventivestacker for bank notes.

[0014] Stacker 1 has storage pocket 4 with contact surface 5 disposed atangle α of about 20° to horizontal 8. Contact surface 5 is firmlyconnected in its upper end area with stacking wheel 3. In the lower endarea of contact surface 5 end tray 16 extends upward at a right angle tocontact surface 5. Contact surface 5 is provided with two slots opentoward the lower end (not visible in the side view), i.e. contactsurface 5 basically consists of three side-by-side, parallel bars in thelower area. End tray 16 is accordingly also formed of three barsconnecting to the bars of contact surface 5.

[0015] Parallel to end tray 16, two side-by-side, parallel bars formingstorage tray 7 extend from the bottom to the top through said slots incontact surface 5. Storage tray 7 is fastened at right angles to slide15 extending under contact surface 5 parallel to contact surface 5.Slide 15 is guided slidably parallel to contact surface 5 in linearguides 14 firmly disposed on contact surface 5, so that storage tray 7parallel to end tray 16 is displaceable in the slots of contact surface5 so as to enlarge distance c between stacking wheel 3 and storage tray7. The end position of storage tray 7 is reached when storage tray 7 islocated at the level of end tray 16. Due to the forked structure ofstorage tray 7 comprising two parallel side-by-side tray portions andthe accordingly offset tray portions of likewise forked contact surface5 with end tray 16 relative to the tray portions of storage tray 7,storage tray 7 can be displaced downward in the displacement directionof slide 15 beyond end tray 16. End tray 16 can also be omitted if anend stop is provided for storage tray 7 instead.

[0016] Via extension spring 9 fastened to support piece 13 on the lowerend of contact surface 5 and fastening bolt 17 on slide 15, said springbeing deflected via a deflection roller (not shown) located in the upperend area of contact surface 5, storage tray 7 is held without additionalexternal application of force in starting position P where minimumdistance c between storage tray 7 and stacking wheel 3 is given. Withsuitably chosen design, minimum distance c can also tend to zero.

[0017] Feeding of storage pocket 4 is effected via stacking wheel 3 bybank notes 2 being introduced into spaces 12 between fingers 11 ofstacking wheel 3 via a supply means not shown. Stacking wheel 3 rotatesabout axis 19, taking notes 2 along in the direction of storage pocket4. Above storage tray 7 or stack 10 already formed of deposited notes 2,individual notes 2 are stripped out between fingers 11 of stacking wheel3 via stripper 18 and deposited on storage tray 7 or on stack 10parallel to storage tray 7, notes 2 lying with edge 6 against contactsurface 5. As soon as stack 10 reaches minimum height c, fingers 11 ofstacking wheel 3 press with their ends on uppermost deposited note 2 atpressure point D, thereby exerting a force on bank note stack 10 in thedisplacement direction of movable storage tray 7.

[0018] The time when the motion of movable storage tray 7 or slide 15begins depends, on the one hand, on the spring constant of stack ofsheets 10 formed and on the biasing force of extension spring 9. Thespring constant of extension spring 9 is selected so that the biasingforce just suffices to restore storage tray 7 reliably to startingposition P upon removal of stack 10 even when the guides are soiled orworn out. On the other hand, the spring constant is selected to beextremely low so that the increase in force when moving storage tray 7is low and the force to be applied to stack of sheets 10 by stackingwheel 3 in the displacement direction is minimal even at maximumexcursion of storage tray 7. For this purpose, very long restoringspring 9 is used which is deflected, as described above. Depending onthe length of the spring, multiple deflection over rolls is alsopossible. The spring constant of stack 10 results from the properties ofnotes 2 forming stack 10 and is in particular dependent on the type ofnotes 2 and the state of notes 2, i.e. the degree of use (old, usednotes or new notes). The force exerted on stack 10 by stacking wheel 3must be dimensioned so that it can overcome the spring force of stack10.

[0019] The example shown in the figure involves a stacker for up to 500bank notes. Maximum pocket height a between stacking wheel 3 and endtray 16 is 111 millimeters in the present example. Distance b betweenstarting position P of storage tray 7 and end tray 16 is 68 millimeters.It follows that storage tray 7 is displaced as of minimum stack height cof 43 millimeters. Different specifications and different choices ofdesign result in accordingly different values.

[0020] Due to the inclined position of storage pocket 4 at angle α ofabout 20° between contact surface 5 and horizontal 8, the motion ofstorage tray 7 is substantially independent of the mass of bank notestack 10, since the frictional forces of edges 6 of notes 2 of stack 10on contact surface 5 and the slope descending force cancel each otherout here. Eliminating the influence of the weight of bank note stack 10makes the passive guidance work, without requiring any separate drive.Thus, driving elements and regulation of the distance between particularlast note 2 and fingers 11 of stacking wheel 3 are unnecessary, so thatthe structure is extremely cost-effective and low in maintenance.

1. A stacker (1) for bank notes (2) having a feeding device (3) fordepositing the bank notes (2) in a storage pocket (4) with variablecapacity, the storage pocket (4) having a contact surface (5) againstwhich the bank notes (2) deposited in the storage pocket (4) lie withone edge (6), and a storage tray (7) on which the bank notes (2) arestacked in the storage pocket (4) flat and parallel to the storage tray(7), and the storage tray (7) of the storage pocket (4) being mountedmovably for changing the capacity of the storage pocket (4),characterized in that the storage pocket (4) is disposed with contactsurface (5) at an angle (α) to the horizontal (8) so that the bank notes(2) stacked in the storage pocket (4) lie with their edges (6) againstthe contact surface (5) and the resulting frictional force between theedges (6) of the bank notes (2) and the contact surface (5)substantially compensates the slope descending force acting on the stack(10) formed of bank notes (2) in the direction of the storage tray (7),and the feeding device (3) exerts a force on the stack (10) whendepositing a bank note (2) at least as of a certain stack thickness (c),thereby moving the storage tray (7) so as to enlarge the capacity of thestorage pocket (4), and the angle (α) between the contact surface (5)and the horizontal (8) is between 20° and 30°.
 2. A stacker according toclaim 1, characterized in that the storage tray (7) is urged by means ofa spring element (9) into a starting position (P) and displaced by thefeeding device (3) against the spring force of the spring element (9).3. A stacker according to claim 1 or 2, characterized in that the angle(α) between the contact surface (5) and the horizontal (8) is about 20°.4. A stacker according to any of claims 1 to 3, characterized in thatthe feeding device (3) includes a stacking wheel having fingers (11)that press on the stack (10) when depositing a bank note (2), therebyexerting a force on the storage tray (7) and displacing the storage tray(7).
 5. A stacker according to any of claims 2 to 4, characterized inthat the spring element (9) has a small spring constant for minimizingthe force to be applied by the feeding device (3) for displacing thestorage tray (7).
 6. A stacker according to any of claims 2 to 5,characterized in that the spring element (9) includes an extensionspring.
 7. A stacker according to claim 6, characterized in that theextension spring is bent between the displaceable storage tray (7) and afixed point of support (13), while being deflected via deflectionelements.